Daniel Simons has become one of the most influential young cognitive scientists in the last decade, co-authoring smash-hit studies in two different fields. He’s probably best-known for the Gorillas in our Midst study, co-authored with Christopher Chabris, where viewers are shown a 45-second video of six students tossing around basketballs. Viewers are instructed to carefully count only the passes between players dressed in white. What they aren’t told is that halfway through the video, a woman dressed in a gorilla suit will walk into the middle of the screen, beat her chest, and walk off. Amazingly, when viewers don’t know about the gorilla in advance, about half of them miss it completely.

Far from being merely an amusing demonstration, the study has important implications, which Simons and Chabris explore in a forthcoming book, The Invisible Gorilla, and on their blog with the same name. I talked with Simons at the Vision Sciences Society meeting in Naples, Florida, as he prepared to introduce a new version of the gorilla study for the annual Best Illusion of the Year contest, held in conjunction with the meeting. You can watch the demonstration, which ranked in top ten illusions of the year, here.

Munger: You’ve now studied inattentional blindness for over 10 years. Can you just tell us a little bit about the origins of the field and your contributions to it?

Simons: The original inattentional blindness work dates back to the mid 1970s with Ulric Neisser. My work on it started in 1998. Neisser came back to Cornell during my final year of graduate school, and I got to talk to him a lot—it was inspirational. The way he did his original studies was to physically superimpose separate films of the activities competing for attention. He filmed three players wearing white shirts passing balls. He filmed three players wearing black shirts passing balls. He filmed a woman with an open umbrella walking through a scene, all separately. Then he superimposed them using mirrors, then filmed the mirrors. The films of the stimuli all have this transparent, ghostly appearance.

When we talked to people about these studies—they all were familiar with them—they often would say, “well, I just think there’s something weird about the displays.” That’s the most regularly recurring critique.

Munger: I have to say, I’ve looked at those displays, and they do look weird. [Here’s an example]

Simons: I think that gave people an easy rationalization for why they might miss something right in the center of a scene. People said, “well, yeah, I missed it, but it looks weird, and if it looked natural, you wouldn’t miss it.” So, when I was teaching an undergraduate lab class at Harvard, we redid the study as a class project. We replicated the originals using better displays, with digital editing. We also decided to try filming the entire thing in a single shot, so nobody could make the excuse if they missed it that they couldn’t see it.

We thought, “we’ve got to try this,” but we didn’t think it was going to work. But then, it did. It was dramatic, and it was so counter-intuitive, that for the first five years I would show people that video, every single time I’d hold my breath, thinking “of course everybody’s going to see it this time.” Because it’s hard to imagine that you couldn’t see it.

Munger: I remember, actually, when I saw you give a talk at APS (The Association for Psychological Science) only maybe 2 or 3 years ago. You gave that demo, and you were surprised because you said it was the first time that nobody in the audience had been fooled by it.

Simons: Yeah, that’s happened only a couple of times. That was after years of having presented it. It was a psychology conference, it was an invited talk, where everyone pretty much knew what I was up to. If I’m invited to give a talk, presumably the people who are inviting me know what I do, so it’s hard to find audiences that are completely naive to what’s coming.

Munger: And of course now, it’s been in TV commercials, and on YouTube…

Simons: Yeah, it’s been copied a number of times.

Munger: So what are some real-world applications of this research?

Simons: I think there are a lot. In inattentional blindness you’re not seeing something that’s right there because your attention is engaged. The most obvious practical application of that is driving. We intuitively think that if something important happens right in front of us, we will see it.

Munger: Like a gorilla.

Simons: Like a gorilla, that’s right. Dan Levin has done studies where he just asked people, would you notice if something like this happens? He shows people the video, gives them the instructions, points out the gorilla, and then asks them “how likely would you be to notice the gorilla if you were doing this task and counting the passes?” Ninety percent of people say they’d notice. Regardless of how you ask that question, you get high confidence, and a high percentage saying “yeah, of course I’d notice that.”

That’s the intuition that’s interesting, and that’s the one that’s dangerous. If we were completely aware of these limits on attention, we wouldn’t do things like talking on cell phone while driving: We would know that it would make us just that much less likely to notice something. But we don’t have that insight into our own awareness. It’s only in that rare case where you actually have an accident that you become aware that you’ve missed something.

There’s a whole class of accidents called “looked but failed to see” accidents. Motorcyclists will swear that they’ve made eye contact with a driver right before the driver turned left in front of them. Some motorcyclists assume that drivers are out to get them. But the reality is that the driver probably never saw them, because the motorcycle is unexpected. When you’re looking for cars, motorcycles are rare; they’re not what you’re looking for, even when they’re distinctive.